Theoretical evidence for a new ultra-high-pressure phase of SiO2
Theoretical evidence for a new ultra-high-pressure phase of SiO2
复制标题
SiO2 超高压新相的理论证据
作者：
K. Park;K. Terakura;Y. Matsui
一个相的二氧化硅密度比stishovite（SiO2-金红石）一直在寻找密集。根据APtshirt等人1和Simakov等人2的建议，SiO2-萤石曾被认为是这种高压相的候选者。然而，随后的理论研究[3，4]表明，SiO2-萤石的密度最多与SiO2-金红石的密度相同，并且在压力低于170 GPa时，其动力学不稳定（参考文献4）。在这里，我们提出了一个替代的假设多晶型二氧化硅与改性萤石（Pa&3macr;）结构作为一个可能的高压相。SiO2-Pa&3macr;将具有4.46 gcm-3的密度（在常压下比SiO2-金红石密度高1.6%），并且在压力为100 =60 GPa时应变得比SiO2-金红石更稳定。这些结果还表明，被广泛接受为地球内部深处主要成分的MgSiO 3-钙钛矿可能在非常高的压力下不稳定。
A phase of silica denser than stishovite (SiO2-rutile) has been searched for intensively. Following the suggestions by APtshuler et al.1and Simakov et al.2, SiO2-fluorite was once regarded as a candidate for such a high-pressure phase. Subsequent theoretical studies3,4revealed, however, that SiO2-fluorite would have at most about the same density as SiO2-rutile and that it would be dynamically unstable at pressures below 170 GPa (ref. 4). Here we propose an alternative hypothetical polymorph of silica with a modified fluorite (Pa&3macr;) structure as a possible high-pressure phase. SiO2-Pa&3macr; would have a density of 4.46 gcm-3(∼6% denser than SiO2-rutile at normal pressures) and should become more stable than SiO2-rutile at pressures of ≳=60 GPa. These results also suggest that MgSiO3-perovskite, which is widely accepted as the major constituent within the Earth's deep interior, may be unstable at very high pressure.
Y.Matsui：矿物中的结构和磁相变。
DOI：
--
发表时间：
--
期刊：
影响因子：
--
作者：
通讯作者：
--